Running it twice means you think you make bad calls. I'm against it. If you lose or take a bad beat while your ahead, you should just top up and keep grinding. The money will come your way if you put your money in good in the long run.
This is just dead wrong. In most all-in on the flop situations, one of the players is ahead --- sometimes materially ahead --- when the players agree to run it multiple times. That player that's ahead agrees to multiple runs to minimize the variance, and in some situations this is clearly a reasonable decision. I am certain that we all run the same in the long run (in terms of "luck"). I am much less sure, however, that we all run the same in the biggest pots (once again, due to randomness, not some rigtard theory). If you generally only play $25K pots but find yourself in a $200K pot, you need a lot of $25K wins to make up for the one loss if your opponent happens to win the big one.
Suppose you're playing a $200K pot where you and your opponent are both all-in on the flop. You hold top two pair vs. villains's nut flush draw. For instance A7 spades vs. KQ off, with a flop of KQ4 and two spades. The guy with two pair is a 64% favorite, but more than 1/3 of the time he'll lose the entire pot.
In this case as the guy holding two pair, I would want to run it three times --- drastically increasing the
odds that the two pair turns out to be profitable, even if the profit is less than max profit. I would probably accept running it twice, though, as it makes it nearly certain (7/8) that I break even at least. You may not want to play it this way, but it's good variance/
bankroll management. If you get into a LOT of $200K pots so you believe that, in the long run, your luck will even out there, I'm fine with not running multiple times --- but there are situations when it's clearly a reasonable decision.
-HooDooKoo